feat: HttpOnly Cookie 登入狀態初始化

app/citizen-frontend/src/pages/self-assessment.vue

@@ -513,7 +513,7 @@
 </template>
 
 <script setup lang="ts">
-import { computed, onMounted, reactive, ref } from "vue";
+import { computed, onMounted, reactive, ref, watch } from "vue";
 import { useRouter } from "vue-router";
 import type {
   ChronicDisease,
@@ -687,16 +687,25 @@ function scrollToPageTop() {
   window.scrollTo({ top: 0 });
 }
 
+function clearErrorMessage() {
+  errorMessage.value = "";
+}
+
 function goToPreviousStep() {
+  clearErrorMessage();
   currentStep.value -= 1;
   scrollToPageTop();
 }
 
 function goToNextStep() {
+  clearErrorMessage();
   currentStep.value += 1;
   scrollToPageTop();
 }
 
+watch(profileForm, clearErrorMessage);
+watch(assessmentForm, clearErrorMessage);
+
 function buildAssessmentRequest(): SelfAssessmentRequest | null {
   if (
     !profileForm.name.trim() ||